Rubber composition for tire sidewall

Abstract

The rubber composition for a tire sidewall includes a rubber component containing not less than 15% by weight of a terminal-modified diene rubber having a number average molecular weight prior to modification of 150000 to 400000, a filler, and a compound (vulcanizing agent) represented by the following general formula (1) in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the rubber component:(wherein R represents a benzyl group, and n represents an integer of 3 to 12.)

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2006-294091, filed on Oct. 30, 2006; the entire contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a rubber composition for a tire sidewall for use as a sidewall rubber of a pneumatic tire.[0004]2. Description of the Related Art[0005]In recent years, a pneumatic tire has been increasingly demanded to be improved in low fuel consumption property. In order to meet such a demand, a terminal-modified diene rubber has been developed (see, Japanese Application Kokai No. 61-103904). The terminal-modified diene rubber is good in compatibility with a filler as a reinforcing agent such as carbon black or silica as compared with general unmodified diene rubbers. For this reason, it is capable of suppressing heat generation and improving t...

AI Technical Summary

Benefits of technology

[0011]The present invention has been completed in view of the foregoing. It is therefore an object of the invention to provide a rubber composition for a tire sidewall which is capable of suppressing the reduction of the hardness due to use of a terminal-modified diene rubber, and achieving the compatibility between the low fuel consumption property and the driving stability without loss of the flexural fatigue characteristic.

[0013]According to an aspect of the present invention, by using a terminal-modified diene rubber having a number average molecular weight prior to modification of 150000 to 400000, and using the specific vulcanizing agent in combination, it is possible to improve the hardness without impairing the effect of improving the low fuel consumption property due to the terminal-modified diene rubber, and without degrading the flexural fatigue characteristic. Thus, it is possible to achieve the compatibility between the low fuel consumption property and the driving stability.

Problems solved by technology

This unfavorably leads to inferior driving stability.

When, to such a reduction in hardness, the enhancement in hardness is tried to be achieved with a conventional technique such as an increase in amount of the filler or a decrease in amount of the oil, the low fuel consumption property tends to be degraded.

In that case, although the hardness and the low fuel consumption property are compatible with each other, the flexural fatigue characteristic is degraded due to the increase in crosslinking density.

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